The low power consumption and high efficiency levels of LEDs versus traditional automotive lighting such as Xenon and halogen are proving desirable to automotive engineers tasked with reducing CO2 emissions and achieving energy savings from all areas of the vehicle.
Front lighting applications that include high-beam, low-beam, daytime running lights (DRLs), and position lights are a particular area where significant energy savings and efficiency gains can be achieved by adopting LEDs—efficiencies that can be translated directly into fuel consumption savings. This is in addition to the important benefits of long operational life, design freedom, and greater functionality that LED-based modules offer versus established approaches.
Being able to successfully develop and implement cost-effective, high efficiency lamp modules that contain strings of high brightness (HB) LEDs is dependent on the design of ECUs that utilise equally efficient system on chip (SoC) solutions that integrate all necessary front lighting specific features including diagnostics and connectivity.
First generation applications for LEDs in front lighting saw them being used as DRLs. Despite only having a low light output and therefore low power consumption, the fact that by definition DRLs are always on when the vehicle engine is running means additional fuel is being used all the time. LED-based DRLs consume in the region of just 9W helping to keep this additional fuel consumption to an absolute minimum. The potential exists for HB LEDs to satisfy all existing front lighting applications that comprise high beam, low beam, DRLs, turn indicators, and fog lights, as well as to provide an optimum solution to new and emerging functions such as beam shaping and motorway spotlighting.
On this evolution path to 100% LED front lighting modules, some vehicle manufacturers are currently selecting only the functions that yield the greatest benefits in terms of energy saving for early conversion to LEDs. The aforementioned DRLs, that are gradually becoming a legal requirement in more countries, are one example. Another is the decision to retain the use of halogen for high beam for the time being—the thought process behind this is that as high beam is used for such a small amount of time (only at night and then only when there are no vehicles approaching from the opposite direction), then total power/fuel savings would be minimal.
As the cost of HB LEDs decreases and their overall performance increases, the trend for new vehicle designs to adopt them will accelerate. This will be further driven by the robust, high efficiency (in the region of 90%) SoC LED drivers such as ON Semiconductor's NCV786XX series that provide a significant step forward compared to switched mode regulators for supporting the medium to high total power requirements of front lighting.
Read this complete article here, which details system-level challenges of incorporating front-lighting LEDs, including temperature and EMI concerns, beam shaping, and current regulation, courtesy of Automotive Designline Europe.